Elongation
Factors - Soluble protein factors required for the elongation of the polypeptide chain are called elongation factor (EF). The two factors isolated initially were called EF-T and EF-G. In prokaryotes EF-T was later shown to consist of two proteins which were called EF-Tu (temperature unstable) and EF-Ts (temperature stable). T refers to transferase activity.
EF-Tu and EF-Ts are required for binding the aminoacyl tRNA (aa.tRNA) to the ribosome. EF-G is involved in the translocation of mRNA.
Eukaryotic elongation factors EF-1and EF-2 (formerly called transferase 1 and 2) correspond to prokaryotic EF- T and EF-G. EF-l resembles prokaryotic EF-Tu in overall activity and size.
